High-Spin Level Systematics inPt186−194and Rotation-Alignment Coupling

Systematic investigations of the shape-transitional nuclei ${}_{}{}^{186}{}_{}{}^{}\mathrm{Pt}$ to ${}_{}{}^{194}{}_{}{}^{}\mathrm{Pt}$ by ($\alpha , \mathrm{xn}\gamma$) reactions have revealed a rich variety of high-spin structural phenomena, which can be qualitatively understood in terms of rotation-alignment coupling and the interplay between collective and single-particle excitation modes. Acute backbending in the positive-parity yrast sequences of ${}_{}{}^{188,190,192,194}{}_{}{}^{}\mathrm{Pt}$ is attributed to the intersection of rotation-aligned ($\nu {i_{\frac{13}{2}}}^{-2\mathrm{}}$) and ($\pi {h_{\frac{11}{2}}}^{-2\mathrm{}}$) bands with the ground bands.